This invention relates to sidewall cores. In determining the physical properties of subterranean formations it is of great assistance to have what is commonly called cores. A core is typically a cylindrical piece of the rock which has been cut from the underground formation and can vary in size and length. A typical size is 1/2 inch diameter and 4 to 6 inches long; although samples can be of larger diameter and of greater length, depending upon the facilities available. One type of core cutter is the type that can be used to cut the cores from the sidewall of a borehole after the borehole has already been drilled. Such a sidewall coring tool is described in U.S. Pat. No. 4,280,569, issued July 28, 1981, to Houston B. Mount, II, inventor, and Standard Oil Company (Indiana), assignee. This invention relates to such a sidewall coring tool.